1. Field of the Invention
The present invention relates to a process for the production of matt epoxide and hybrid powder coatings.
2. Description of the Background
DE-A 2324 696 describes a process for the production of matt coatings, in which epoxy resins are cured using salts of aromatic polycarboxylic acids, especially pyromellitic acid, and cyclic amidines. An essential feature of this process described in DE-A 23 24 696 is that it is not the individual components but their reaction products, the salts, which are employed.
Furthermore, it is known that equally matt surfaces to those above are, in fact, prepared by the simultaneous use of two individual curing agents, cyclic amidine and polycarboxylic acid, as is the case when the matt curing agent in salt form, consisting of the same individual components, is employed. However, in this case, surface texturing must be considered, as well as the possibility of poor physical properties of the product.
It is also known that only salts of cyclic amidines with trimellitic acid and/or pyromellitic acid are suitable for the production of matt epoxy powder coatings. The corresponding salts of phthalic acid, isophthalic acid and terephthalic acid, on the other hand, cure with epoxy resins to give glossy films.
A need therefore continues to exist for a curing agent to prepare matt surfaces of improved characteristics.